diff --git a/PIL/Jpeg2KImagePlugin.py b/PIL/Jpeg2KImagePlugin.py
index ff6ca4b35..66069802e 100644
--- a/PIL/Jpeg2KImagePlugin.py
+++ b/PIL/Jpeg2KImagePlugin.py
@@ -40,8 +40,8 @@ def _parse_codestream(fp):
 
     size = (xsiz - xosiz, ysiz - yosiz)
     if csiz == 1:
-        if (ssiz[0] & 0x7f) > 8:
-            mode = 'I'
+        if (yrsiz[0] & 0x7f) > 8:
+            mode = 'I;16'
         else:
             mode = 'L'
     elif csiz == 2:
@@ -100,7 +100,7 @@ def _parse_jp2_header(fp):
             size = (width, height)
             if unkc:
                 if nc == 1 and (bpc & 0x7f) > 8:
-                    mode = 'I'
+                    mode = 'I;16'
                 elif nc == 1:
                     mode = 'L'
                 elif nc == 2:
@@ -116,7 +116,7 @@ def _parse_jp2_header(fp):
                 cs = struct.unpack('>I', content[3:7])[0]
                 if cs == 16:   # sRGB
                     if nc == 1 and (bpc & 0x7f) > 8:
-                        mode = 'I'
+                        mode = 'I;16'
                     elif nc == 1:
                         mode = 'L'
                     elif nc == 3:
@@ -126,7 +126,7 @@ def _parse_jp2_header(fp):
                     break
                 elif cs == 17:  # grayscale
                     if nc == 1 and (bpc & 0x7f) > 8:
-                        mode = 'I'
+                        mode = 'I;16'
                     elif nc == 1:
                         mode = 'L'
                     elif nc == 2:
diff --git a/Tests/images/16bit.cropped.j2k b/Tests/images/16bit.cropped.j2k
new file mode 100644
index 000000000..c12df0cd7
Binary files /dev/null and b/Tests/images/16bit.cropped.j2k differ
diff --git a/Tests/images/16bit.cropped.jp2 b/Tests/images/16bit.cropped.jp2
new file mode 100644
index 000000000..0f6685a46
Binary files /dev/null and b/Tests/images/16bit.cropped.jp2 differ
diff --git a/Tests/test_file_jpeg2k.py b/Tests/test_file_jpeg2k.py
index b662124b4..b763687f7 100644
--- a/Tests/test_file_jpeg2k.py
+++ b/Tests/test_file_jpeg2k.py
@@ -120,6 +120,42 @@ class TestFileJpeg2k(PillowTestCase):
         self.assertEqual(j2k.mode, 'RGBA')
         self.assertEqual(jp2.mode, 'RGBA')
 
+    def test_16bit_monochrome_has_correct_mode(self):
+
+        j2k = Image.open('Tests/images/16bit.cropped.j2k')
+        jp2 = Image.open('Tests/images/16bit.cropped.jp2')
+
+        j2k.load()
+        jp2.load()
+
+        self.assertEqual(j2k.mode, 'I;16')
+        self.assertEqual(jp2.mode, 'I;16')
+
+    def test_16bit_monchrome_jp2_like_tiff(self):
+
+        tiff_16bit = Image.open('Tests/images/16bit.cropped.tif')
+        jp2 = Image.open('Tests/images/16bit.cropped.jp2')
+        self.assert_image_similar(jp2, tiff_16bit, 1e-3)
+
+    def test_16bit_monchrome_j2k_like_tiff(self):
+
+        tiff_16bit = Image.open('Tests/images/16bit.cropped.tif')
+        j2k = Image.open('Tests/images/16bit.cropped.j2k')
+        self.assert_image_similar(j2k, tiff_16bit, 1e-3)
+
+    def test_16bit_j2k_roundtrips(self):
+
+        j2k = Image.open('Tests/images/16bit.cropped.j2k')
+        im = self.roundtrip(j2k)
+        self.assert_image_equal(im, j2k)
+
+    def test_16bit_jp2_roundtrips(self):
+
+        jp2 = Image.open('Tests/images/16bit.cropped.jp2')
+        im = self.roundtrip(jp2)
+        self.assert_image_equal(im, jp2)
+
+
 if __name__ == '__main__':
     unittest.main()
 
diff --git a/libImaging/Jpeg2KDecode.c b/libImaging/Jpeg2KDecode.c
index 76c1d169b..97ec81003 100644
--- a/libImaging/Jpeg2KDecode.c
+++ b/libImaging/Jpeg2KDecode.c
@@ -160,7 +160,7 @@ j2ku_gray_i(opj_image_t *in, const JPEG2KTILEINFO *tileinfo,
     case 1:
         for (y = 0; y < h; ++y) {
             const UINT8 *data = &tiledata[y * w];
-            UINT32 *row = (UINT32 *)im->image[y0 + y] + x0;
+            UINT16 *row = (UINT16 *)im->image[y0 + y] + x0;
             for (x = 0; x < w; ++x)
                 *row++ = j2ku_shift(offset + *data++, shift);
         }
@@ -168,7 +168,7 @@ j2ku_gray_i(opj_image_t *in, const JPEG2KTILEINFO *tileinfo,
     case 2:
         for (y = 0; y < h; ++y) {
             const UINT16 *data = (const UINT16 *)&tiledata[2 * y * w];
-            UINT32 *row = (UINT32 *)im->image[y0 + y] + x0;
+            UINT16 *row = (UINT16 *)im->image[y0 + y] + x0;
             for (x = 0; x < w; ++x)
                 *row++ = j2ku_shift(offset + *data++, shift);
         }
@@ -176,7 +176,7 @@ j2ku_gray_i(opj_image_t *in, const JPEG2KTILEINFO *tileinfo,
     case 4:
         for (y = 0; y < h; ++y) {
             const UINT32 *data = (const UINT32 *)&tiledata[4 * y * w];
-            UINT32 *row = (UINT32 *)im->image[y0 + y] + x0;
+            UINT16 *row = (UINT16 *)im->image[y0 + y] + x0;
             for (x = 0; x < w; ++x)
                 *row++ = j2ku_shift(offset + *data++, shift);
         }
@@ -516,7 +516,8 @@ j2ku_sycca_rgba(opj_image_t *in, const JPEG2KTILEINFO *tileinfo,
 
 static const struct j2k_decode_unpacker j2k_unpackers[] = {
     { "L", OPJ_CLRSPC_GRAY, 1, j2ku_gray_l },
-    { "I", OPJ_CLRSPC_GRAY, 1, j2ku_gray_i },
+    { "I;16", OPJ_CLRSPC_GRAY, 1, j2ku_gray_i },
+    { "I;16B", OPJ_CLRSPC_GRAY, 1, j2ku_gray_i },
     { "LA", OPJ_CLRSPC_GRAY, 2, j2ku_graya_la },
     { "RGB", OPJ_CLRSPC_GRAY, 1, j2ku_gray_rgb },
     { "RGB", OPJ_CLRSPC_GRAY, 2, j2ku_gray_rgb },